title: Cortical gyrification induced by fibroblast growth factor 2 in the mouse brain.
abstract: Gyrification allows an expanded cortex with greater functionality to fit into a smaller cranium. However, the mechanisms of gyrus formation have been elusive. We show that ventricular injection of FGF2 protein at embryonic day 11.5-before neurogenesis and before the formation of intrahemispheric axonal connections-altered the overall size and shape of the cortex and induced the formation of prominent, bilateral gyri and sulci in the rostrolateral neocortex. We show increased tangential growth of the rostral ventricular zone (VZ) but decreased Wnt3a and Lef1 expression in the cortical hem and adjacent hippocampal promordium and consequent impaired growth of the caudal cortical primordium, including the hippocampus. At the same time, we observed ectopic Er81 expression, increased proliferation of Tbr2-expressing (Tbr2(+)) intermediate neuronal progenitors (INPs), and elevated Tbr1(+) neurogenesis in the regions that undergo gyrification, indicating region-specific actions of FGF2 on the VZ and subventricular zone (SVZ). However, the relative number of basal radial glia-recently proposed to be important in gyrification-appeared to be unchanged. These findings are consistent with the hypothesis that increased radial unit production together with rapid SVZ growth and heightened localized neurogenesis can cause cortical gyrification in lissencephalic species. These data also suggest that the position of cortical gyri can be molecularly specified in mice. In contrast, a different ligand, FGF8b, elicited surface area expansion throughout the cortical primordium but no gyrification. Our findings demonstrate that individual members of the diverse Fgf gene family differentially regulate global as well as regional cortical growth rates while maintaining cortical layer structure.
authors.affiliation: Child Study Center, Department of Neurobiology, and Kavli Institute for Neuroscience, Yale University, New Haven, Connecticut 06520, USA.
authors.forename: Brian G
authors.initials: BG
authors.lastname: Rash
authors.forename: Simone
authors.initials: S
authors.lastname: Tomasi
authors.forename: H David
authors.initials: HD
authors.lastname: Lim
authors.forename: Carol Y
authors.initials: CY
authors.lastname: Suh
authors.forename: Flora M
authors.initials: FM
authors.lastname: Vaccarino
mesh_terms: D000818:Animals; D000963:Antimetabolites / Q000494:pharmacology; D001369:Axons / Q000502:physiology; D001923:Brain Chemistry / Q000187:drug effects; D001973:Bromodeoxyuridine / Q000494:pharmacology; D002452:Cell Count; D002540:Cerebral Cortex / Q000033:anatomy & histology* / Q000187:drug effects / Q000254:growth & development*; D002552:Cerebral Ventricles / Q000378:metabolism / Q000502:physiology; D018076:DNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D003720:Densitometry; D000229:Dependovirus; D005260:Female; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D049452:Green Fluorescent Proteins; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D051821:Lymphoid Enhancer-Binding Factor 1 / Q000096:biosynthesis / Q000235:genetics; D051379:Mice; D019579:Neocortex / Q000033:anatomy & histology / Q000254:growth & development; D011247:Pregnancy; D012313:RNA / Q000096:biosynthesis / Q000302:isolation & purification; D060888:Real-Time Polymerase Chain Reaction; D060509:Wnt3A Protein / Q000096:biosynthesis / Q000235:genetics
chemical_list: D000963:Antimetabolites; D018076:DNA, Complementary; C497574:Lef1 protein, mouse; D051821:Lymphoid Enhancer-Binding Factor 1; D060509:Wnt3A Protein; C555511:Wnt3a protein, mouse; D016222:Fibroblast Growth Factor 2; D049452:Green Fluorescent Proteins; D012313:RNA; D001973:Bromodeoxyuridine